I’m assuming the bikes will go on a tail hitch. The paddle boards will go on a roof rack. So you really are only talking about room for two dogs.
IMHO, literally any car will do the job. In fact, you might find an actual trunk for your gear much more effective than the back of a 4runner. SUVs have huge cargo space but it’s actually quite ineffective without careful packing. The space things sit on without being piled on top of other gear really isn’t much different than any hatchback or car trunk.
As for mileage, a lot really depends on your drive. Unless you actually drive free range highway, without urban traffic, just erase those highway mileage numbers from your head. Even if you do, subtract 10-20% because the mileage calcs are done at a slower speed.
If you do a lot of surface streets or stop and go, honestly look at a prius or similar, possible the Lexus RX450h hybrid which gets stunningly good (supposedly) MPG.
